The Glow Dreaming comes equipped with three settings for the duration of the functions: 2 Hour, 4 Hour or ON.
When using either the 2 hour or 4 hour timers, the Glow Dreaming will run for exactly this amount of time and then all three features (the LED, Slow Wave Sound Therapy and humidifier) will stop running.
The ON setting lets the Glow Dreaming run indefinitely until manually switched off. The LED and Slow Wave Sound Therapy will continue all night and the humidifier, when filled to the maximum amount of 500ml, will run continuously for 10-12 hours, or until the unit is switched off manually.
If you fill the humidifier below the 500ml line then it will run for less time. If you were to do this and the humidifier uses all the water after a few hours, the LED and Sound will continue to run as per usual.